Technical Field
The disclosure relates to a processing device or the like that is electrically connected to a drive controller for driving a control object and performs a process of determining control parameters for drive control.
Description of Related Art
In general, feedback control is used to move a control object to follow a target trajectory. For example, in an articulated robot, a servomotor of each joint axis is controlled by a controller of the robot to cause a position of a finger part of the robot to follow a previously set (instructed) target trajectory using feedback control. However, in common feedback control, since a delay in response invariably occurs at each servomotor, there is a problem that an actual trajectory of the robot deviates from the target trajectory. With respect to this problem, techniques for adopting feed forward control and controlling a position of a robot to always match a command position have been presented. For example, in a technique disclosed in Japanese Laid Open No. 2006-15431 (Patent Document 1), in control of an articulated robot arm driven by a plurality of motors, a future position is estimated from a current position using a predetermined position model, and a current position command is corrected by a difference between the estimated position and a target trajectory, namely by an error fraction of a direction perpendicular to the target trajectory, and thereby followability of the target trajectory is improved.
When the future position is estimated using the position model as described above and there is a big change in a trajectory characteristic of an actual control object, for instance, a switch from rectilinear movement to arc movement, accuracy of the estimation is not always favorable, and suitable correction of the position command becomes difficult. Therefore, in a technique disclosed in Japanese Patent No. 5340486 (Patent Document 2), a position command is corrected using information about a boundary point position of a shape of a target trajectory (a command path) and about a moving direction near the boundary point position, and thereby trajectory followability corresponding to a change in a trajectory characteristic is improved. A technique relevant to so-called model follow-up control may also be used in order to enhance servo control performance of a control object. In this model follow-up control technique, a model part that models a feedback system including a control object and a controller is formed in a control device and an output from the model part is reflected in the feedback system, and thereby the servo control performance is improved.
However, although the trajectory followability can be enhanced using the model follow-up control as in the related art, in the case of synchronous control in which a plurality of control shafts are synchronized and subjected to drive control, if followability of each control shaft differs, the trajectory caused by the synchronous control, namely the actual trajectory in which output of each control shaft subjected to the synchronous control is synthesized and formed, is likely to deviate from the target trajectory. For example, in the case where the control shafts are two orthogonal shafts, although the target trajectory of the synchronous control is a circular trajectory, when followability between the control shafts deviates, the actual trajectory is likely to become an elliptical trajectory as a result.
The disclosure was made to provide a technique in which, when a plurality of control objects are subjected to synchronous control according to so-called model follow-up control, an actual trajectory according to the synchronous control is made to follow a target trajectory as much as possible.
In the disclosure, when a plurality of control objects are synchronously controlled, responsiveness at control model parts for model follow-up control corresponding to the control objects is formed to be the same. With this configuration, an actual trajectory according to the synchronous control can be made to suitably follow a target trajectory.